Anatomy of a Crawler: MAIN

[Sabaot]

Morning, evening or whatever time zone you have.

Starting today I plan to create a series of, well - lets say articles, with basic informations and explanations about simple RC
Crawler build and mechanics involved. At the moment of writing it I'm such a newb/noob (tho I urge you not to use "noob"
as a description of a newbie since it has a very peiorative connotations) in that particular subject but I'm trying to get as
much as I can to fully understand the basics of a RC Crawler.

Anyway, only recently had I started with RC Crawlers and as many of you new to this hobby folks I have little knowledge,
lots of questions and other "hows". So during my search I figured out that I can help myself (and others as well) by creating
something that will put all(most all) basic knowledge about RC Crawlers in one place. I realise that will NOT be ultimate
guide. It wasn't planned as one, it's just a starting place from where you can jump into deeper water.

I won't hide that I aim for a star. And I need posts to achieve that. Also, I do not wish to simply find a thread and say
something irrelevant like "nice rig" or "I'd want to know that as well". I want to be a part of this community, a part that
contributes is some way. So I decided to collect data and present it as a first step. A place where most of a newbie
questions are answered already.

Because there is a lot of knowledge I plan to make multiple threads, each focused on certain aspect of a RC Crawler. This
post will work as a Main Menu and includes a very first part.

Table of content (clickable links to specific topics, no link means no article available yet).

Anatomy of a RC Crawler, by Sabaot.
1. RC abbreviation, Tx, Rx, binding (below)
2. What a RC Crawler is?
http://www.rccrawler.com/forum/newb...awler-part-2-what-rc-crawler.html#post4481199

3. Motor, aka ENGINE.
http://www.rccrawler.com/forum/newb...wler-part-3-motor-aka-engine.html#post4481213

4. Transmission
http://www.rccrawler.com/forum/newb...-crawler-part-4-transmission.html#post4481219

5. Differentials
http://www.rccrawler.com/forum/newb...crawler-part-5-differentials.html#post4481223

6. Reduction Unit
http://www.rccrawler.com/forum/newb...rawler-part-6-reduction-unit.html#post4481228

7. Power Supply
http://www.rccrawler.com/forum/newb...-crawler-part-7-power-source.html#post4481237

8. Chasis
9. Shocks
10. Cleaning and maintenance
11. Water Resistancy
12. Miscallenous


So lets get started.

****************************
1. RC abbreviation, Tx, Rx, binding
****************************

We talk about RC Crawlers but what exactly RC Crawler is? First, lets explain quickly RC abbreviation - it stands for Radio
Controlled: a cordless way of operating a device using a handheld transmitter that communicates with a device's receiver
via radio waves. Transmitter (Tx for short) and receiver (Rx) makes a set, commonly named "a radio". One Tx can
communicate with multiple Rxs. Well, not at the same time as it may cause serious problems (imagine that your model
runs accordingly to your mate's commands).

As we are with radios lets talk about "binding". As mentioned before one Tx can operate multiple Rx's. Normally you get
one Tx and one Rx connected to each other (bound). It means that when powering your model the installed Rx will "listen"
to your Tx only. When you get another model you have two options:
- get a new set of radio to operate / use included set (as in most RTR versions) - more expensive way
- get just a new Rx and bind it to your existing Tx - cheaper solution.

But what binding exactly is. Well, this is a method of "teaching" your Tx how to find and communicate with your Rx. Various
manufacturers have various methods of binding additional Rx's (if applicable) so for specific method you need to refer a
manual. As a note, some brands developed automatic binding process (eg. Traxxas Link) and new "unbound" Rx will bind
with first Tx it finds while Tx will remember by itself a new Rx and its setup. Pretty handy.

Now, we explained what a RC means and how it works... no, we didn't explain how it works exactly. All we know so far is it
uses radio waves. To be precise - 2.4 GHz (giga hertz) wave spectrum, older versions (still in use) were running on 72 MHz
wave spectrum. A quick note: 1Hz = 1 cycle per second, clock runs at 1Hz. 72Mhz = 72*10^6 Hz, 2.4GHz = 2.4*10^9 Hz (24
and 8 zeros). Ok, physics looks weird so lets leave it as it is. What is important is the answer on the following question:
which is better?

2.4GHz. Simple as it is. This technology is less susceptible to interference than 72MHz, it also provides better overall range
of operation. A little comparison:
72 MHz range: 300 - 1000 ft (~90 - 300m)
2.4 GHZ range: 600 - 1200 ft (~180 - 360m)
Also note that maximum range depends on various external conditions: power input, weather, sorrounging buildings, power
lines, line of sight and of course - manufacturer of a device. You can enhance range but it requires an additional devices,
such a signal amplification unit, additional anttenae.

Before you even start long range voyages you should first check your radio range in your sorroundings. You will need 2
people for that, one stays with Tx, other moves avay and makes notes.

WARNING: DISCONNECT MOTOR FROM THE MODEL FIRST AS IT MAY TURN FULL SPEED IN CASE OF SIGNAL LOSS.
MOTOR'S POWER CABLES DISCONNETION WILL SUFFICE. AND MAKE THIS WARNING A SERIOUS ONE AS IT MAY PREVENT
MODEL DAMAGE/LOSS AND/OR INJURY.

Ok, range testing procedure itself. To make it simple and clear, lets assume you (operator with Tx) stays in place while your
partner carries model away, stopping at certain distance marks (like 10ft/5m). While your partner stops you move steering
wheel as you would like to turn and your partner notes if models wheels turn. If so he proceeds and increase distance
between you two. He does so untill model stops reacting to your signals. When it does it means it reached its maximum
operating distance. Note that value. For safety reasons try not to exceed 80% of that value.

Now, is above really that important? In case or RC Crawlers - not necessairly. But it's good to know that to not be surprised
in the future. Knowlegde about max operating distance should be known but it's essential with flying/swimming models
and in some cases with road RC Cars. Crawlers usually don't go farther than 65ft/20m from you.

Now, I think we have all basic info about control covered. If I have missed something, said wrong - feel free to correct, add.
Then I will change above and indicate a contributor so everyone would know who to bother with stupid questions (jk).

Aah... I forgot about one thing. So basic that I'm really ashamed. How many channels does a Crawler need and what a
channel is?

Channel (CH for short) is a communication route between Tx and Rx which passes only ONE kind of signal (steering, speed,
any other), aimed for only one action. Typical car Tx requires only 2CH; 1 for acceleration/brakes, 2nd for steering
(left/right). That's all, ground vehicles move in 2-dimention space so only 2CHs are required. Climbing doesn't count as
vehicle still moves on the ground - 3rd dimension applies to flying/swimming models (ascending/descending).

Of course radios have more channels available, for example Traxxas Summit has a 4CH radio, typical 2CH + additional 2CH
for transmission gear change (crawling/racing) and differential locking (3-way switch: front/rear/both).

For a RC Crawler purpose we need just 2CH, tho 3rd one wouldn't hurt (for future gear change) and maybe 4th for some
bling-bling like remote lighs on/off. Basic is 2CH, the rest is up to personal preferences.

And with that optimistic accent I will end. For more information aobut other topics of a RC Crawler click a link in the Menu.

Hope you liked it, more to come.
Enjoy.

 

[pajey]

Hi and welcome to rcc. I'd like to first thank and praise you for your threads on an rccrawler and well... congrats. Because they are pretty lengthy and look knowledgeable.(I couldn't be bothered reading all of them only a couple). Take no offense to this but do you have a life? Haha. They are really long. But will be quite helpful for noobs.

 

[Calderwood]

I'm sure this will be valuable for some new members. Two questions, what do you mean when you say you "I won't hide that I aim for a star. And I need posts to achieve that." And why do you use the return button like you are on a typewriter?

Edit: I just skimmed through some more of it and noticed a couple of things. FM should have considerably more range than 2.4ghz. FPV guys use fm so they can fly out considerably further than what 2.4ghz systems allow. Also you description of channels and their uses largely ignores comp crawling. Moa crawlers use three channels, one steering and two throttle channels mixed to allow independent control of the front and rear motors. Supers use all three of these same functions but then add a fourth channel for rear steering.

 

[Sabaot]

Hey,

and thanks for kind words.

Take no offense to this but do you have a life?

None taken, and yes - I have a life, quite busy and I don't have much time for my research.

I won't hide that I aim...

Forum rules - to get full access to the forum's resources I need a history of at least 30 posts and 30 days of time. Or pay $20 which unfortunately isn't an option.

why do you use the return button like you are on a typewriter?

Sadly, conversion bug appeared. Originally I write in Notepad and then copy/paste finished text into new post. And when I does that I get weird formatting. Minor issue.

About radios and channels - most times I'm focusing on a simple Crawler, that means motor on chasis, simple transmission, some body and suspension with wheels far below. That's why you won't find a word about moa's. But with your note I can expand that particular topic with your comments.

As for FM and FPV - mind that with flying you don't have an obstacles that could limit your operating range (trees, line of sight, buildings, etc.). Most of the times there is a clear and straight line between you and your model. Ground models don't have that luxury.

Also, FPV is a rather specific kind of RC sport and requires additional transmitting devices and signal amplification units. I mentioned that. For all I know far more spread are 2.4 GHz radios for steering with 5.8 GHz link for video feed.

And range comparison I just took from internet sources so I can't be held responsible for their accuracy. And as i already mentioned several times - my work aim is to present in one place a wide range of basic informations about RC Crawlers, a starting step from which you can go further and explore every detail of that hobby. A guide for all new people who saw a Crawler and want one but don't know a thing about it.

Cheers.

 

[lemonhead]

no offense but all your info you posted is already on this site in one way or the other."thumbsup"

 

[Sabaot]

I'd be really surprised if it wouldn't. But there is a slight problem with all these already posted informations - they are spread over the entire forum, piece here, piece there. My goal was to try to put it into one place and make somehow a fairly complete guide about basic info. Generally speaking people are lazy when it comes to data search. Hence so many same questions being asked so frequently. Instead of searching lets ask how to calculate a gear ratio. For the 2354626 time

My attempt was to answer those basic questions before they would be asked. Also it was a good way for me to learn a thing or two about crawlers as trying to write it I had to take a close look on almost every aspect of a rig. Kind of self learning technique by repetition.

 

[Calderwood]

I commend you effort but spreading misinformation doesn't benefit anyone. Maybe you might want to discuss things you are more confident about.

 

[jboehler04]

I commend you effort but spreading misinformation doesn't benefit anyone. Maybe you might want to discuss things you are more confident about.

x2 its a good thought but thats why there is a search option here. everything ive searched for has came up and if it doesnt or cant get a very clear answer then ill ask for more clarity. but most everything ive need an answer for has been fulfilled with the search function. your threads have a good idea but way to lengthy and the information and can be close to misleading. also what works on one crawler might not work on the next. everyone has their own ideas and personal likes for their setup. and most rig specific forums already have a sticky thread stating stuff that is must have upgrades and already tired attempts at what works and doesnt. and personally you have a thread asking if stuff works together and now your posting threads of what works to me seems like its misleading info. and another thing if your pulling this info off other sites or product info you should say where your getting it. jus my .02

 

[Billy D]

I don't understand what you are trying to do? If a newbie needs info as I do from time to time, I start with reading Harleys threads first if that doesn't answer my question then I would seek the help of a pro like Harley and others on here with thousands of post. I would not read a how to thread from someone just trying to get 30 posts. IMO

 

[PutTheOldShoeOn-Kurt]

I commend you effort but spreading misinformation doesn't benefit anyone. Maybe you might want to discuss things you are more confident about.

If you see this post leads to misinformation, please then correct it. I found this post quit useful wit information and it really helps me to get start on RC crawling. I really appreciated the author’s effort.

 

[Boomer75]

In general I get the concept and appreciate the significant effort put into it. In my relatively short time as a member here, we see the same questions repeated every few weeks. That is not necessary a bad thing as that means more people are newly entering the hobby, which means more product development and availability due to the growing market. I think the constant repeats are partially because this site is huge, full of content and I think it takes a while to understand how to navigate all the content. The search feature is pretty good and there are sticky threads on core topics like terminology under the newbie section and one on painting. However, I think it takes people a while to understand how to use them and where to look.

I also agree that going to sources like Harley's youtube page, Scale Builders Guild youtube page, Exocaged, RcReviews, JRHolmes youtube page and others will get beginners up to speed fast. These two sources complement one another and you see a fair amount of cross referencing. Maybe the next sticky thread can be an updated list of crawler focused youtube sites for info. I know there was a thread here discussing favorite youtube pages a while back. That would be good info for people with servo, motor and kit review questions for starters.